Journal of Molecular Evolution

, Volume 40, Issue 3, pp 326–330

Properties of a general model of DNA evolution under no-strand-bias conditions

  • J. R. Lobry

DOI: 10.1007/BF00163237

Cite this article as:
Lobry, J.R. J Mol Evol (1995) 40: 326. doi:10.1007/BF00163237


Under the hypothesis of no-strand-bias conditions, the Watson and Crick base-pairing rule decreases the complexity of models of DNA evolution by reducing to six the maximum number of substitution rates. It was shown that intrastrand equimolarity between A and T (A*T*) and between G and C (G*C*) is a general asymptotic property of this class of models. This statistical prediction was observed on 60 long genomic fragments (>50 kbp) from various kingdoms, even when the effect of the two opposite orientations for coding sequences is removed. The practical consequence of the model for estimating the expected number of substitutions per site between two homologous DNA sequences is discussed.

Key words

DNA evolutionNo-strand biasCoding sequence



Watson and Crick base pairing rule (A:T, G:C)


Intrastrand type-1 parity rule (ij, m(i,j)m(\(\bar i,\bar j\)))


Intra strand type-2 parity rule (A*T*, G*C*)

Copyright information

© Springer-Verlag New York Inc. 1995

Authors and Affiliations

  • J. R. Lobry
    • 1
  1. 1.Laboratoire de Biométrie, CNRS URA 243Université Claude BernardVilleurbanne CedexFrance